Resilient head assembly having resilient mount

ABSTRACT

A printer head assembly for use in high speed printers of the dot-matrix type. The assembly is comprised of a one-piece hollow die cast member having a rear wall for mounting a plurality of driving solenoids. Reciprocally mounted print wires extend from each of their associated solenoids mounted at the rear wall through the hollow interior of the die cast member with their free ends mounted so as to be substantially flush with the front wall of the die cast member. Hollow tubular guide means are provided within the interior of the die cast housing to maintain an appropriate curvature for each of their associated print wires which extend therethrough. A jewel bearing is provided at the forward end of each of the guide wires to provide a low friction jewel bearing for each of the print wires to prevent abrasive wear of the print wires. A jewel bearing is provided at the front end of the die cast housing for arranging the forward end of each of the print wires substantially along an imaginary straight line in very closely spaced fashion. At least one retaining plate is mounted within the die cast housing at a point intermediate the forward and rearward ends. A plurality of apertures are provided in the mounting plate, each of which is adapted to receive one of said tubular guide means. The diameter of each of the openings in the mounting plate is substantially greater than the outer diameter of each of the tubular guides. A suitable resilient material such as, for example, silicone rubber is affixed to one surface of the mounting plate so as to surround each of the guide tubes and to resiliently secure the guide wires to the mounting plate. The resilient mounting affords a cushioning effect to attenuate and absorb any transverse motion imparted thereto during either the impact or return movement of the print wires so as to significantly increase the useful operating life. If desired, a pair of such mounting plates having the aforesaid resilient mounting means for the guide tubes may be employed.

United States Patent [191 6 Howard in] 1 3,782,520 Jan. 1, 1974 RESILIENTHEA D ASSEMBLY HAVING RESILIENT MOUNT [75] Inventor; Robert Howard, Roslyn, NY.

[73] Assignee: Centronics Data Computer Corp.,

Hudson, NH.

[22] Filed: Nov. 4, 1971 [21] Appl. No.: 195,558

[52] US. Cl. 197/1 R, 101/93 C Primary Examiner-Edgar S. Burr Attorney-Samuel Ostro lenk et al.

[571 ABSTRACT A printer head assembly for use in high speed printers of the dot-matrix type. The assembly is comprised of a one-piece hollow die cast member having a rear wall for mounting a plurality of driving solenoids. Reciprocally mounted print wires extend from each of their associated solenoids mounted at the rear wall through the hollow interior of the die cast member with their free ends mounted so as to be substantially flush with the front wall of the die castmemiber. Hollow tubular guide means are provided within the interior of the die cast housing'to maintain an appropriate curvature for each of their associated print wires which extend therethrough. A jewel bearing is provided at the forward end of each of the guide wires to provide a low friction jewel bearing for each of the print wires to prevent abrasive wear of the print wires. A jewel bearing is provided at the front end of the die cast housing for arranging the forward end of each of the print wires substantially along an imaginary straight line in very closely spaced fashion. At least one retaining plate is mounted within the die cast housing at a point intermediate the forward and rearward ends. A plurality of apertures are provided in the mounting plate, each of which is adapted to receive one of said tubular guide means. The diameter of each of the openings in the mounting plate is substantially greater than the outer diameter of each of the tubular guides. A suitable resilient material such as, for example, silicone rubber is affixed to one surface of the mounting plate so as to surround each of the guide tubes and to resiliently secure the guide wires to the mounting plate. The resilient mounting affords a cushioning effect to attenuate and absorb any transverse motion imparted thereto during either the impactor return movement of the print wires so as to significantly increase the useful operating life. If desired, a pair of such mounting plates having the aforesaid resilient mounting means for the guide tubes may be employed.

3 Claims, 5 Drawing Figures RESlllJlllENT HEAll) ASSEMBLY HAVING RESILIENT MOUNT The present invention relates to printers and more particularly to a novel printer head assembly and driving means therefor for use with high speed printers of the dot-matrix type wherein resilient mounting means are employed to reduce and cushion movement of the print wires in a direction transverse to their normal direction of movement.

BACKGROUND OF THE INVENTION Wire matrix printers are well known in the prior art. One of the earliest types of wire matrix printers is comprised of a plurality of wires arranged in matrix fashion (i.e. regular rows and columns) for making impact through a ribbon to a paper document whereby the wires are selectively energized to form characters, numerals or other symbols. The earliest types of wire matrix printers were capable of printing either words or entire characters. The next development in the art consisted of wire matrix printers having a plurality of wires arranged in a row by column fashion for printing individual characters, numbers or symbols. Selected ones of the print wires were driven against the paper document to form the desired character or symbol. The print wires are then shifted one position to the right to print the next character, number or symbol whereby shifting occurs in an intermittent fashion. Since a large plurality of separate driving mechanisms must be provided f sas 9 thsiztintnir s. tfstszamn sifij sash drive mechanisms are required for a X7 dot matrix printer) the amount of mass which must be moved to perform printing is quite appreciable. The shortcomings in the art resulted in the development of wire matrix printers in which only a single vertically aligned column to print wires are employed. The print wires are selectively driven against the inked ribbon and paper document to form one of the five columns of the numher, character, or symbol. The character upon wich the print wire assembly is mounted is then shifted one position to the right to print the next column. This operation continues until all five columns have been printed to ultimately form the character or other symbol.

Since it is desirous to provide impact printers capable of high speed operation, the print wires undergo high speed movement in both the impact and return directions which cause the print wires to undergo abrupt movement in the direction transverse to the normal movement of the print wires resulting in undue wearing thereof.

A BRIEF DESCRIPTION OF THE INVENTION The present invention is characterized by providing a high speed impact printer of the dot matrix type in which the printer head assembly, which is capable of high speed operation, is provided with resilient means for positioning and aligning the print wires whereby transverse movement of the print wires relative to the normal direction of movement is both attenuated and cushioned so as to significantly reduce the wearing of parts, thereby increasing the operating life thereof.

The present invention is comprised of a printer head assembly having solenoid driven print wires. The entire printer head assembly, including the solenoid driver, is moved across the paper document, preferably at a constant rate of speed. The arrangement of the printer head assembly is such as to provide a lightweight compact structure so as to minimize the mass which is moved across the paper document, enabling the structure to move at relatively high speeds.

The printer head assembly is comprised of a onepiece die cast housing having a rear wall for mounting each of the solenoids. The lightweight high speed solenoid drivers are mounted through tapped apertures provided in the rear surface of the hosuing whereby the solenoid drivers are clustered together in a rather compact fashion. Each of the solenoid drivers have their armatures mechanically coupled to an associated slender print wire. The print wires are arranged to converge together at the forward end of the housing where they are preferably aligned along an imaginary straight line and arranged in very closely spaced fashion. The jewel bearing mounted at the front face of the housing effectively provides low friction guiding means for the forward ends of the print wires, as well as significantly reducing any frictional engagement between the forward ends of the print wires and the inked ribbon which may otherwise occur even when the print wires are in their retracted position, due to the close spacing between the front face of the housing and the inked ribbon.

Each of the print wires are mounted for reciprocating movement within hollow tubular guide members extending between the forward and rearward faces of the die cast housing. At least one mounting plate is provided within the hollow housing at a position intermediate the forward and rearward ends thereof. The mounting plate is provided with a plurality of apertures, each being adapted to receive one of the hollow tubular guide means. The forward ends of each of the tubular guide means are preferably provided with a jewel bearing for significantly reducing frictional engagement between the forward end of each of the tubular guide means and their associated reciprocating print wires.

Each of the openings provided in the mounting plate are of a diameter which is significantly greater than the outer diameter of the associated tubular guide means which it receives. A resilient material such as, for example, silicone rubber is affixed to one surface of the mounting plate so as to surround all of the tubular guide means and resiliently secure same to the mounting plate. The resilient material acts toboth attenuate and cushion movement of the print wires and hence the tubular guide means in a direction transverse to the normal reciprocating movement of the print wires so as to significantly reduce wearing of the components and thereby significantly increase the operating life thereof.

OBJECT OF THE lNVENTlON It is therefore one object of the present invention to provide a novel printer head assembly for use in impact printers of the dot-matrix type wherein the printer head assembly includes resilient mounting means for reducing and cushioning movement of the print wires in a direction transverse to their normal reciprocating movement.

BRIEF DESCRIPTION OF THE FIGURES The above as well as other objects of the present invention will become apparent when reading the accompanying description and drawing in which:

FIG. 1a is a top plan view showing a printer head assembly designed in accordance with the principles of the present invention.

FIG. lb shows an elevational view of the printer head assembly of FIG. 1a with portions thereof being sectionalized to facilitate an understanding thereof.

FIG. 2a shows a sectional view of the forward end of one of the tubular guide means of FIGS. la and 1b.

FIG. 3 shows a sectional view of one of the mounting plates of FIG. la looking in the direction of arrows AA.

DETAILED DESCRIPTION OF THE FIGURES FIGS. la and 1b show a printer head assembly comprised of a one-piece die-cast housing member 11 having a pair of flanges 12a and 12b which extend to the sides of the housing as well as extending below the housing and which are provided with openings 13 for receiving suitable fastening means to secure the housing 11 upon a movable carriage assembly (not shown for purposes of simplicity).

The rear end of member 11 is provided with an upwardly projecting wall 14 having a plurality of tapped openings 15 whose longitudinal axes are aligned so as to be substantially perpendicular to their associated exterior surfaces 14a, 14b, 14c and 14d, shown in FIGS. 1a and lb. The openings are aligned so that their longitudinal axes intersect at a remote point, which point lies on an imaginary line which is preferably coincident with the central axis of opening 15'.

Each of the openings is tapped to threadedly engage a threaded collar 17 of a print solenoid 18. Each of the solenoid assemblies is similarly provided with threaded collars for threadedly engaging an associated one of the tapped apertures 15 (or 15 Each solenoid has a slender solenoid print wire 19 (or 19) connected to its movable armature (not shown, for purposes of simplicity) and projecting outwardly through an opening provided at the forward end of each threaded collar 17,

which print wires extend from the forward end of each solenoid'assembly and through the hollow interior of the housing 11 so as to extend substantially to the forward end thereof in a manner to be more fully described. A preferred design of the solenoid is shown in copending application Ser. No. 179,627, filed Sept. 13, 1971 and assigned to the assignee of this invention.

Die-cast member 11 is further provided with a rear mounting portion 20 comprised of inwardly directed projections 21 and 22 formed integrally with the side walls 1 1a and 1 lb, respectively. Each of the projections is provided with a narrow slot 21a and 22a, respectively, for receiving a substantially thin planar sheet 23 provided with a plurality of openings, such adapted to receive a hollow tubular guide member 47. Planar sheet 23 is inserted within the narrow slot 21a and 22a so that its bottom edge rests against the bottom surface 11c of the die-cast member 11.. An epoxy is provided at 25 to retain planar sheet 23 in position.

Die-cast member 11 is further provided with a forward mounting portion 27 comprised of first and second projections 28 and 29 extending inwardly from side walls 1 la and 1 lb and integrally formed therewith. Each of the projections is provided with a narrow slot 28a and 29a respectively, for receiving a thin planar sheet 30 whose opposite marginal edges are fitted within slots 28a and 29a. The bottom edge of sheet 30 rests against the base portion 11b of die-cast member 11 and is epoxied as shown at 31 to retain the sheet in position.

Sheet or plate 30 is similarly provided with a plurality of openings 24, each adapted to receive an associated one of said tubular guide means 47.

Print wires 19 (and 19') extend forwardly from their associated solenoids so each of the print wires pass through the openings 24 in plates 23 and 30, with the forward free ends of the print wires additionally being mounted to reciprocate within a final jewel bearing assembly 34 which is positioned in very close proximity to the inked ribbon so as to minimize frictional engagement of the forward ends of the print wires with the inked ribbon and thereby prevent the wires from engaging the inked ribbon when in the retracted or reset position.

Each of the print wires 19 (and 19) are mounted for reciprocal movement within hollow guide tubes 47, each of which extend between front wall lle and rear wall 14 of die-cast member 11. The hollow tubular guides are secured within associated openings 24 provided in plates 23 and 30. Although not shown for purposes of simplicity, one such tube guide is provided for each print wire 19 (19'). Each of the tube guides are provided at their left-hand ends with a jewel bearing arrangement which may take the form of that shown in FIG. 2. As shown therein, one end of tube guide 47 is provided with a central opening 47a. The outermost interior portion of central opening 47a is drilled or otherwise machined so as to provide an enlarged diameter portion 47b. A jewelbearing 24 is fitted within the enlarged diameter portion as shown, preferably in a pressfitted manner. The extreme end 47c of the tube is then swaged over the right-hand end of jewel 24 so as to firmly retain the jewel in position within the tube guide. It should be understood that either end or both ends of the tube guides may be provided with jewel bearings in the manner shown. It should further be understood that any other suitable arrangement may be employed for securing a jewel bearing such as, for example, that taught in FIG. 4b of copending application Ser. No. l79,627, filed Sept. 13, 1971 and assigned to the assignee of the present invention. Obviously, any other technique for mounting jewel bearings may be employed.

As shown best in FIG. 3 of the present application, each of the hollow tubular guides is resiliently mounted to either plates 23, 30, or both. FIG. 3 shows a sectional view of one such mounting. Plate 23 is provided with an opening 24 whose diameter is substantially greater than the other diameter of tubular guide 47 which, in turn, reciprocally mounts slender print wire 19'.

The rearward surface of mounting plate 23 has applied thereto a suitable resilient material such as, for example, silicone rubber 48 which is adapted to surround and intimitely contact each of the tubular guides in the immediate region of the openings provided in plate 23. Preferably, some of the resilient material enters into the hollow region defined by the interior surface of opening 24 and the exterior surface of tubular guide 47.

The resilient material acts to provide a resilient mounting for the tubular guides.

From a consideration of FIGS. la and 1b, the print wires can be seen to be curved in the plane of both figures. Due to the extremely high speed operation of the print wires, which wires are rapidly accelerated in the forward direction (see arrow P of FIG. la) to impact the inked ribbon and paper document and are further rapidly accelerated in the rearward direction (see arrow R of FIG. 1a) to return to the reset position, the print wires undergo a whipping effect whereby the portions of the print wires may experience abrupt movement or whipping in a direction transverse to the direction of reciprocating movement. The resilient material serves to both cushion and attenuate the guide tubes and hence the print wires so as to minimize movement thereof other than in the forward and rearward directions, thereby substantially reducing wearing of the print wires and their associated guide tubes to thereby yield an assembly which has an extremely long and useful operating life even after repeated high speed use.

The resilient material which has been found satisfactory for this use is marketed under the trademark RTV. However, any other suitable resilient material may be employed. Alternatively, resilient grommet members 49 such as are shown in FIG. 3a may be employed for the-resilient mounting with equal success. However, the resilient silicone rubber or other materials similar thereto is found to be more desirable due to the simplified nature of its application;

If desired, only one or the other of the mounting plates may be provided with the resilient mount described herein, dependingly only upon the needs of the user. Alternatively, both sides of plates 23 and 30 may be coated with resilient material, if desired.

It can be seen from the foregoing description that the present invention provides novel resilient novel mounting means for use in high speed print assemblies of the dot-matrix type where lateral movement of the print wires is both attenuated and minimized so as to reduce wearing and increase the useful operating life thereof.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.

What is claimed is:

l. A printer head apparatus for use in printers of the dot matrix type comprising:

a housing having front and rear walls joined by a pair of side walls and a floor defining a hollow interior;

a plurality of print wire solenoid driving means secured to said rear wall;

each of said solenoid driving means including a thin reciprocating print wire of uniform diameter over its length and extending through said housing rear wall with its forward free end extending through said hollow interior and terminating adjacent said front wall;

spacing means secured within said front wall for maintaining the free ends of said print wires in a predetermined alignment;

a print wire positioning and guiding assembly mounted within said housing between said front and rear walls respectively for maintaining a plurality of said print wires in a curved configuration which extends between said front and rear walls, said assembly having a plurality of openings;

hollow tubular guide means each adapted to receive one of said print wires; each of said tubular guide means extending through an associated one of said openings; resilient means secured to said assembly and secured to and surrounding said tubular guide means in the region of said assembly for cushioning and attenuating transverse movement of the print wires and tubular guide means; the outer diameters of said tubular guide means being less than the di ameters of said openings to form an annular gap between each opening and its associated guide means whereby movement of the tubular guide means in a direction transverse to the reciprocating movement of said print wires is permitted; said resilient means filling said gaps; said resilient means being silicone rubber.

2. The apparatus of claim 1 wherein the forward ends of the opening in said tubular guide means are each provided with a jewel member to reduce wearing due to sliding contact between said jewel members and said print wires.

3. The apparatus of claim 1 wherein said silicone rubber covers one face of said assembly and surrounds each of said tubular guide means in the gap region between said openings and said tubular guide means. 

1. A printer head apparatus for use in printers of the dot matrix type comprising: a housing having front and rear walls joined by a pair of side walls and a floor defining a hollow interior; a plurality of print wire solenoid driving means secured to said rear wall; each of said solenoid driving means including a thin reciprocating print wire of uniform diameter over its length and extending through said housing rear wall with its forward free end extending through said hollow interior and terminating adjacent said front wall; spacing means secured within said front wall for maintaining the free ends of said print wires in a predetermined alignment; a print wire positioning and guiding assembly mounted within said housing between said front and rear walls respectively for maintaining a plurality of said print wires in a curved configuration which extends between said front and rear walls, said assembly having a plurality of openings; hollow tubular guide means each adapted to receive one of said print wires; each of said tubular guide means extending through an associated one of said openings; resilient means secured to said assembly and secured to and surrounding said tubular guide means in the region of said assembly for cushioning and attenuating transverse movement of the print wires and tubular guide means; the outer diameters of said tubular guide means being less than the diameters of said openings to form an annular gap between each opening and its associated guide means whereby movement of the tubular guide means in a dirEction transverse to the reciprocating movement of said print wires is permitted; said resilient means filling said gaps; said resilient means being silicone rubber.
 2. The apparatus of claim 1 wherein the forward ends of the opening in said tubular guide means are each provided with a jewel member to reduce wearing due to sliding contact between said jewel members and said print wires.
 3. The apparatus of claim 1 wherein said silicone rubber covers one face of said assembly and surrounds each of said tubular guide means in the gap region between said openings and said tubular guide means. 